Earth auger construction



w. M. TROEPPL 3,235,018

EARTH AUGER CONSTRUCTION Feb. 15, 1966 Filed July 17, 1964 2 Sheets-Sheet 1 mvEyTor-z. MMMM f, Edi/ P1.

Feb. 15, 1966 w. M. TROEPPL 3,235,018

EARTH AUGER CONSTRUCTION Filed July 17, 1964 2 Sheets-Sheet 2 INVENTOR. W/LL/AM M. TROEPPL A TTOPNE) United States Patent 3,235,018 EARTH AUGER CONSTRUCTION William M. Troeppl, Santa Clara, Calif., assignor, by

direct and mesne assignments, of one-half to Gerald A.

Petersen, Santa (Ilara, Calif., and one-half to Anita E.

Petersen, Saratoga, Calif.

Filed July 17, 1964,5221. No. 383,464 8 Claims. (61. 175-391) This application is a continuation-in-part of copending application Serial No. 309,120, filed September 16, 1963, now abandoned.

This invention relates to a new and improved earth auger construction. More particularly, the invention relates to an earth auger of the twin helix type wherein teeth on one side of the central axis of the auger are displaced in an axial direction lower than the corresponding teeth on the opposite side of said axis.

The present invention comprises an improvement on Petersen Patent No. 2,578,014, and has the advantages of the construction of said patent. Foremost among such advantages is the fact that the twin helix design provides two equal cutting areas balancing the thrust so that the auger automatically stays centered in the hole which is being dug and is not thrust against the side of the hole. Such construction materially reduced maintenance cost and eliminates the need for back thrust shoes conventionally required on other types of augers.

Another feature of the design of said Patent No. 2,578,014 is that the teeth are positioned in a staggered step-back pattern. The tooth nearest the central axis of the auger is the lowest and accordingly makes the first furrow closest to the center of the hole. The next nearest tooth to the central axis is on the opposite side of the auger, and such tooth makes a furrow immediately outside the first-mentioned tooth. Among the advantages of such staggered construction are the reduction in the amount of power required to turn the auger for digging action.

A still further feature of the construction of the auger of Patent No. 2,578,014 is that the direction in which the tooth points is the direction of travel in each instance. As the radius or distance of the tooth from the central axis varies, the angular position of the tooth changes correspondingly. This construction is of particular advantage when the auger encounters rocks, since-only one tooth ordinarily strikes the rock and thus has a better opportunity to fracture the same or, in any event, to pry under the rock so that upon lifting the auger the rock maybe split or raised out of position.

There are numerous other advantages and features of the invention of Patent No. 2,578,014 not heretofore mentioned, which have resulted in considerable commercial success of said auger. The present invention comprises an improvement on said auger construction but retains the advantages thereof heretofore mentioned.

A distinguishing feature of the present invention is the fact that the teeth on one side of the twin helix are lower than the level of the corresponding teeth on the other side. Thus, the first two lowermost teeth on one side dig concentric furrows in which the center lines of the groove are spaced apart two tooth widths with a ridge between the furrows. The first tooth on the opposite side of the auger cuts off the top of the ridge between the first-mentioned two furrows. Accordingly, the teeth on the first (or lower) side of the auger dig spaced furrows of increasing radial distance distance from the central axis, while the teeth on the second (or higher) side of the auger cut away the ridges between adjacent furrows. It is thus a feature of the present construction that two teeth on the lower side dig into the soil before the first tooth on the higher side contacts the ridge between the two furrows. Improved penetration of very hard and compact soils results, one side ripping the soil and the other side tclettiring the bottom of the hole for the next ripping con- The foregoing construction enables augers to dig in h ghly-compacted soil and soil resembling rock in conslstency, types of soils which have not heretofore been successfully dug by angers. Such a cutting action facilitates installation of utility poles, tower footings and similar jobs with rapidity, efficiency and low power requirements.

In a preferred embodiment of the present invention,

the set of teeth on the lowermost or first side are of a particular construction shown in patent application Serial No. 203,492, filed June 19, 1962, now Patent No. 3,136,077. This shape tooth has a ripping or explosive action relative to hard caliche type soils which is highly effective in areas where earth augers have not heretofore been used successfully. In said preferred embodiment, the teeth on the second or higher side of the auger are of the type shown in US. Patent Nos. 2,877,574, 2,952,085 and 2,968,880. The broader cutting edges of the latter teeth are effective in cutting off the ridges between furrows dug by the more sharply pointed curved teeth.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

FIG. 1 is an elevational view of a twin helix auger head in accordance with the present invention.

FIG. 2 is a schematic view showing the digging action of alternate teeth on one side and the other of the auger.

FIGS. 3 and 4 are respectively longitudinal sectional views taken substantially along corresponding lines in FIG. 2.

FIG. 5 is a schematic cross-sectional view through a bore hole dug in accordance with the present invention and showing in fragmentary form the outline of the teeth which perform the digging operation.

FIG. 6 is a schematic bottom plan view of the auger showing the staggered relationship of the teeth on opposite sides of the auger.

FIG. 7 is a view similar to FIG. 1 of a modified auger.

FF. 8 is a fragmentary side elevational view of the modification of FIG. 7, showing a portion of an auger head tooth holder attached thereto and teeth.

Referring first to FIG. 1 of the drawings, there is illustrated a modification of that type of twin helix auger shown in Petersen Patent No. 2,578,014. The auger comprises a central shaft or stem 11 to the lower end of which is attached by means of a connector 12, such as that connector shown in Patent No. 2,870.995, a pilot bit 13 such as that shown in Patent No. 2.773,.673. Welded to the stem 11, or formed integrally therewith, is a pair of radially opposed, helical-shaped blades 14, 16. The lower ends 17, 18 of blades 14, 16, respectively, are bent downwardly at an angle as ramps and form seats for shank plates 19, 21, respectively. The shank plates 19. 21 are secured to extensions 17, 18 by means of bolts 22 and nuts 20.

A feature of the present invention is the fact that the bottom edge of downward extension 18 is lower than that of downward extension 17 by about one inch as measured in the direction of the central axis of stem 11. In the embodiment of FIG. 1, extension 18 is longer than extension 17 and this accomplishes the desired result of making the cutting edges of the teeth on one side of the auger lower than on the other. An alternative means is illustrated in FIGS. 7 and 8, as hereinafter described.

Each of the shank plates 19, 21 provide means for securing in position a plurality of cutting teeth. The teeth 23 on shank plate 21 are preferably of a particular shape shown in patent application Serial No. 203,492 and the means of attachment of said teeth 23 to said shank plate 21 is as shown in FIGS. and 6 of said patent application. The shank plates are formed with H-shaped attachment means consisting of top and bottom members 24, 26 and an inter-connecting web 27. Web 27 is formed with a transverse hole 28 and the sides of web 27 rearward of hole 28 are formed with grooves 29. A short piece of resilient material, such as rubber or neoprene 31, extends through hole 28 and is bent backwardly along groove 29. Tooth 23 is formed with prongs 32 at the proximal end thereof divided by a slot 33 extending forwardly from the proximal end thereof. The distance between the sides of slot 33 is substantially equal to the thickness of web 27. Accordingly, the rearward ends of resilient insert 31 bear against the substantially vertical side edges of slot 33 and retain tooth 23 in its holder against unintentional dislodgmcnt. The distal side edges 161 of tooth 23 are essentially vertical. As viewed in plan (FIG. 3), edges 161 extend forwardly in a smooth inward curve from parallel proximal side edges 125. At the distal ends of curve 161, distal side edges 162 are parallel to each other and to the sideedges 125 of the proximal end. The width at vertical transverse front end 163 is only about one-third thedistance between the side edges 125 of the proximal portion. Extending down the center of the top of the tooth is spine 166. Spine 166 slopes up from the forward end of the proximal portion of the tooth at about a 45 angle to a peak 167 about one-fourth the distance forward of the distal end of the tooth and then slopes downwardly-forwardly at a 30 angle toward the front end. The thickness of the tooth at peak 167 is about twice that at the prongs at the proximal end of the tooth and at the front end 163 about onehalf that at the proximal end. The corner 168 between the front end of spine 166 and end 163 is bevelled in a triangular surface 168. The flanks 169 of the spine are curved in arcuate surfaces of relatively large radius. Rearwardly of spine 166 surfaces 171 of the tooth are blended to smoothly fill out the transition from the fiat top surfaces of the proximal end to peak 167.

The bottom surface of the distal portion is almost flat but has a slight'concavity of maximum extent indicated by reference numeral 172. This shape augments penetration of the soil.

On the side opposite the teeth 23 are teeth 36. Said teeth are of the type shown in FIG. 2 of Patent No. 3,057,091, or alternatively that form shown in Patent No. 2,877,574, or FIGS. 1 to 9, inclusive, of Patent No. 2,952,085.

The means of attachment of teeth 36 to the holders therefor in shank plate 19 is substantially identical with that shown in FIGS. 2 and 3 for the tooth 23, and the same reference numerals followed by the subscript a are used to represent corresponding parts. It will be understood that this means of attachment is essentially that shown in Patent No. 2,968,880, FIGS. 1 to 6, inclusive.

The teeth 36 have forwardly converging top and bottom surfaces 37, 38, truncated by a transverse end 39 providing top and bottom cutting edges 41, 42, making the tooth reversible. End 39 extends across the entire width of the tooth as contrasted with the narrow cutting edge 163 of tooth 23.

Directing attention now to FIG. 6, the reference numeral 46 represents the central axis of stem 11. A series of concentric circles 47a, 47b, 47c and 47a are at equallyspaced intervals from axis 46 the spacing between circles being about twice the width of end 39 of tooth 36, while circle 47c represents the outside diameter of the hole dug by the auger. Pilot bit 13 digs a hole having a diameter substantially equal to circle 47a. As shown in the accompanying drawings and herein described, there are four teeth 23a to 23d connected to shank plate 21. It will be understood that although four teeth are shown on each side of the auger, nevertheless the number may be increased or decreased depending upon the size, capacity and design of the auger. The innermost tooth 23a is centered at circle 47a and tooth 23b at circle 47b, tooth 23c, at circle 47c, and tooth 23d at circle 47d. Further, each successive tooth proceeding outwardly has its lowermost point at slight distance higher than the preceding tooth (see FIG. 1) so that (ignoring the central hole 48 formed by pilot bit 13) the bottom of the hole shown in FIG. 5 slopes outwardly-upwardly. As also shown in FIG. 5, the teeth 23a, 23b, 23c, 23d, which form the sloping bottom, are indicated by corresponding reference numerals. The teeth on the righthand side of FIG. 5 form furrows 49a to 49d, inclusive, with ridges 51, 52, 53 thcrebetween. Again directing attention to FIGS. 1 and 6, it will be seen that the direction each tooth assumes in plan view is at a varying angle with relation to the radial line 56 as compared with adjacent teeth, the teeth axes being tangent to the respective circles 23a, 23b, 23c, 23d. Further, the cutting edges of the teeth assume different angles with relation to a horizontal plane. In other words, each tooth is slightly twisted about a longitudinal axis so that when the auger is rotated the cutters cut angular surfaces relative to each other.

The teeth 36 are staggered relative to teeth 23. Thus, as best shown in FIG. 6, tooth 36a is centered between circles 47a and 47b, approximately midway between said circles. Tooth 26b is midway between circles 47b and 47c; tooth 360 is midway between circles 47c and 47d; tooth 36a. is midway between circles 47d and 47c. The outer edge of tooth 36d is tangent to circle 47 and thus defines the side edge of the hole. The placement of teeth 36a to 36d, inclusive, as shown in FIG. 5 is such that said teeth out otf the ridges 51, 52, 53, left by the teeth 23a to 23d, inclusive.

The effect of the use of teeth on one side lower than on the other side is that the lower teeth 23 create furrows 49a to 49e in the bottom of the hole with ridges 51 to 53 between the furrows and the teeth 36 on the other side of the auger cut ofl. the ridges and leave a relatively smooth conical surface.

It will be understood that although the shape of teeth 23 ditfers from the shape of teeth 36, nevertheless the present invention contemplates that identical teeth may be used on each side of the auger, namely, preferably the teeth 36 used on both sides, but with the teeth on one side lower than the corresponding teeth on the opposite side.

Valve gate 61 may be hingedly connected by means of hinge pins 62 to the upper ends of the helical blades 14, 16. The construction and function of such gates 61 is zrplained in Patent No. 2,578,014, column 3, lines 18 to In the modification of FIGS. 7 and 8, the lower ends of auger blades 14b, 16b, respectively, are at the same elevation (as contrasted with extension 17, 18 of FIG. 1). Shank plate 21b has an upper portion 71 which lies on top of the lower end of blade 16b and is bolted thereto by bolts 22 and nuts 20. The intermediate portion 72 is bent downward at approximately a right angle to upper portion 71 and has a length of about one inch. The lower portion 73 is bent at about a right angle to portion 72, so that it is parallel to portion 71 but depressed about one inch. The tooth attachment means on shank plate 21b is preferably the same as in the preceding modification.

On the opposite side of the auger shank plate 1% is straight. The overall lengths of shank plate 19b, 21b are the same. Accordingly, the lower or working end of plate 21b is about one inch lower than 19b.

In other respects the modification of FIGS. 7 and 8 is the same as in the preceding embodiment. The same reference numerals are applied in the drawing and the specific construction is not herein described in detail.

It will be further understood that the structure shown in the accompanying drawings may be welded to the lower end of a single pitch or double pitch flight auger. See, for example, Patent No. 2,863,640, where an offset boring head for an auger is attached to a single flight auger.

The construction of the present invention permits digging in highly compacted soils and in locations and geographical areas which have hitherto resisted boring operations of this type. In the preferred form of the invention herein illustrated using teeth 23 and 36 of different structure, furrows 49a to 492, inclusive, are formed in the bottom of the hole with an explosive action which shatters highly compacted soils and the ridges 51, 52, 53 are cut off by the teeth 36 on the other side of the auger. Thus, on the right hand side of FIG. 5 there is a ripping action and on the left hand side there is a subsequent smoothing out of the ridges 51 to 53. It will, however, be understood that where such ripping action is not essential, that the teeth on both sides may be essentially the same, preferably of the type shown by reference numeral 36.

Although the foregoing invention has been described in some detail, by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be practiced within the spirit of the invention and scope of the appended claims.

What is claimed is:

'1. An earth auger comprising a stem, a plurality of first teeth, said first teeth terminating at their lower ends in first cutting edges, a plurality of second teeth, said second teeth terminating at their lower ends in second cutting edges, first means mounting said first teeth for rotation with said stem each slanting downward and spaced different distances from said stem, and second means mounting said second teeth for rotation with said stem each slanting downward and spaced different distances from said stern,

said first cutting edges being lower than corresponding second cutting edges, said first cutting edges being spaced different radial distances from the axis of said stem with radial gaps between the paths of movement of said first cutting edges, said first cutting edges being at higher elevations proceeding outward from said stem, said first cutting edges creating furrows in the bottom of the hole. dug by said anger with ridges between furrows corresponding .to said gaps between the paths of movement of said first cutting edges,

said second cutting edges being approximately as Wide as said gaps and positioned radial distances from said axis the same as said gaps and spaced from said stem intermediate corresponding first teeth, the elevation of each second cut-ting edge being intermediate the elevation of the first cutting edge closer to and the first cutting edge farther from said axis,

said second cutting edges positioned so that each said second cutting edge cuts off one of said ridges,

said second cutting edges being twisted about their longitudinal axes to cut angular surfaces relative to each other and said surfaces together assuming a relatively smooth conical surface.

2. An auger according to claim 1, in which said first means comprises a first plate removably mounted for rotation with said stem, a plurality of first tooth holders on said first plate, said first teeth individually rernolvably positioned in said first tooth holders, and in which said second means comprises a second plate removably mounted for rotation with said stem, a plurality of second tooth holders on said second plate, said second teeth individually removably positioned in said second tooth holders,

said first and second plates diametrically opposed.

3. An auger according to claim '1, in which said first means comprises an upper portion secured to said stem, a downturned intermediate portion and a lower portion generally parallel to said upper portion but depressed relative thereto.

4. An auger according to claim v1, which further comprises first and second auger flights on said stem, said first flight terminating lower than said second flight, said first means and said second means fastened to said first and second flights, respectively.

5. An auger according to claim 1, in which said first teeth are higher on the outside of said auger than the inside and said second teeth are also higher on the outside than the inside.

6. An auger according to claim 1, in which said first teeth are narrower at their forward end edges than said second teeth.

7. An earth auger comprising a stem, diametrically opposed first and second plates removab-ly mounted for rotation with said stem, said first plate terminating lower in an axial direction than said second plate, a plurality of first tooth holders on said first plate, downward slanting first teeth individually removably positioned in said first tooth holders, a plurality 01f second tooth holders on said second plate and downward slanting second teeth individually removably positioned in said second tooth holders, said first teeth being lower than corresponding second teeth, said second teeth spaced from the central axis of said auger intermediate corresponding first teeth, the cutting edges of said first teeth being positioned to create furrows in the bottom of the hole dug by said auger with ridges between furrows, said second teeth being positioned so that each said second tooth cuts off one of said ridges to leave a relatively smooth conical surface, at least one of said first teeth having a proximal portion having substantially parallel side edges and a distal portion having forward side edges parallel to each other and to said parallel side edges of said proximal portion with smoothly inwardly curved edges interconnecting said side edges of said proximal portion and said forward side edges of said distal portion, said distal portion forward side edges being substantially closer together than said proximal side edges, the top surface of said distal portion formed with a longitudinally extending spine sloping downwardly-forwardly, said top surface of said distal port-ion on either side of said spine being concave, the front end of said tooth being truncated and square, the bottom of said distal portion being substantially flat.

8. An earth auger comprising a stem, diametrically opposed first and second plates removably mounted for rotation with said stem, said first plate terminating lower in an axial direction than said second plate, a plurality of first tooth holders on said first plate, downward slanting first teeth individually re-movably positioned in said first tooth holders, a plurality of second tooth holders on said second plate and downward slanting second teeth individually removably positioned in said second tooth holders, said first teeth being lower than corresponding second teeth, said second teeth spacedfrom the central axis of said auger intermediate corresponding first teeth, the cutting edges of said first teeth being positioned to create furrows in the bottom of the hole dug by said auger with ridges between furrows, said second teeth being posirtioned so that each said second tooth cuts off one of said ridges to leave a relatively smooth conical surface, said first teeth being narrower at their forward end edges than said second teeth, each said first tooth having a central spine on its top surface and concavely curved flanks on either side of said spine, each said second tooth having fiat forwardly converging top and bottom surfaces and the forward end of said second tooth extending transversely across the full width of said second tooth.

(References on folfowing page) References Cited by tile Examiner UNITED STATES PATENTS 1/ 1929 Rorabeck 37-142 4/1950 Henning 175-383 12/ 195 1 Petersen 175-392 7/ 1956 Nelson 37-142 2,800,302 7/1957 McClennan 175-391 2,855,181 10/1958 Olsen 175-391 2,877,987 3/1959 Petersen 175-397 X 3,136,077 6/1964 Troeppl 37-142 CHARLES E. OCONNELL, Primary Examiner. 

8. AN EARTH AUGER COMPRISING A STEM, DIAMETRICLALY OPPOSED FIRST AND SECOND PLATES REMOVABLY MOUNTED FOR ROTATION WITH SAID STEM, SAID FIRST PLATE TERMINATING LOWER IN AN AXIAL DIRECTION THAN SAID SECOND PLATE, A PLURALITY OF FIRST TOOTH HOLDERS ON SAID FIRST PLATE, DOWNWARD SLANTING FIRST TEETH INDIVIDUALLY REMOVABLY POSITIONED IN SAID FIRST TOOTH HOLDERS, A PLURALITY OF SECOND TOOTH HOLDERS ON SAID SECOND PLATE AND DOWNWARD SLANTING SECOND TEETH INDIVIDUALLY REMOVABLY POSITIONED IN SAID SECOND TOOTH HOLDERS, SAID FIRST TEETH BEING LOWER THAN CORRESPONDING SECOND TEETH, SAID SECOND TEETH SPACED FROM THE CENTRAL AXIS OF SAID AUGER INTERMEDIATE CORRESPONDING FIRST TEETH, THE CUTTING EDGES OF SAID FIRST TEETH BEING POSITIONED TO CREATE FURROWS IN THE BOTTOM OF THE HOLE DUG BY SAID AUGER WITH RIDGES BETWEEN FURROWS, SAID SECOND TEETH BEING POSITIONED SO THAT EACH SAID SECOND TOOTH CUTS OFF ONE OF SAID RIDGES TO LEAVE A RELATIVELY SMOOTH CONICAL SURFACE, SAID FIRST TEETH BEING NARROWER AT THEIR FORWARD END EDGES THAN SAID SECOND TEETH, EACH SAID FIRST TOOTH HAVING A CENTRAL SPINE ON ITS TOP SURFACE AND CONCAVELY CURVED FLANKS ON EITHER SIDE OF SAID SPINE, EACH SAID SECOND TOOTH HAVING FLAT FORWARDLY CONVERGING TOP AND BOTTOM SURFACES AND THE FORWARD END OF SAID SECOND TOOTH EXTENDING TRANSVERSELY ACROSS THE FULL WIDTH OF SAID SECOND TOOTH. 